Anyone can be a contributor to an Apache project. Being a contributor simply means that you take an interest in the project and contribute in some way, ranging from asking sensible questions (which documents the project and provides feedback to developers) through to providing new features as patches.
If you become a valuable contributor to the project you may well be invited to become a committer. Committer is a term used at the ASF to signify someone who is committed to a particular project. It brings with it the privilege of write access to the project repository and resources.
In Dolphinscheduler community, if a committer who have earned even more merit, can be invited to be a part of the Project Management Committee (PMC).
One thing that is sometimes hard to understand when you are new to the open development process used at the ASF, is that we value the community more than the code. A strong and healthy community will be respectful and be a fun and rewarding place. More importantly, a diverse and healthy community can continue to support the code over the longer term, even as individual companies come and go from the field.
More details could be found here.